How to Convert a PDF to Grayscale (Black and White)

To convert a PDF to grayscale, the tool renders each page through a canvas, converts every pixel’s colour channels to a luminance value, and saves the result as a new PDF. The output has no colour data at all — just shades of grey from white to black. The entire process happens in your browser, so the file never leaves your device.

Why convert a PDF to grayscale?

Colour printing costs three to five times more than black-and-white on most laser printers, and significantly more on inkjet. If you are printing a 50-page colour report to hand out at a meeting, converting to grayscale first can cut the print cost in half.

Beyond printing, there are other reasons people strip colour from PDFs:

• Sending to a monochrome fax or copier — older office equipment handles only black and white. Colour documents can produce unexpected output or fail entirely.
• File size reduction — colour pages store RGB channel data for every pixel in every image. Grayscale pages store only a single luminance channel, which is smaller. A colour-heavy PDF can shrink noticeably.
• Accessibility and print-neutral formatting — some documents use colour to convey information (red text for warnings, green for approval). A grayscale version forces you to check whether the content is still clear without colour, which is a useful accessibility exercise.
• Archiving — PDF/A archival formats often discourage colour profiles. A grayscale document eliminates potential ICC profile issues.
• Redacting sensitive colour-coded data — if a document uses colour-coded categories that you want to neutralise before sharing, grayscale removes that encoding.

How to convert a PDF to grayscale step by step

This takes under a minute for most documents:

Effect on file size

The size change depends on what is inside your PDF:

The size reduction comes from two things: the re-rendered images now store one channel instead of three, and the canvas re-encoding applies JPEG compression to images. If you want maximum size reduction, use the Compress PDF tool on the grayscale output.

What to know about client-side grayscale

The browser-based grayscale tool works by rendering each page to an HTML canvas at full resolution. This has two implications worth knowing:

• Text becomes rasterised — the output PDF contains page images, not live text. The text will look identical to the original but will not be selectable or searchable. If you need searchable text in the output, consider an OCR tool after conversion.
• Fonts are embedded as images — this means the output is not dependent on any particular font being installed, which is good for compatibility, but it increases file size slightly compared to a font-embedding grayscale approach.

For most use cases — printing, sharing, archiving, faxing — these limitations do not matter. For documents where text searchability is critical, a server-side Ghostscript conversion preserves the text layer while converting the colour space.

Why processing in the browser matters

Most PDF converters send your file to a remote server. Grayscale conversion is often used on sensitive documents — coloured financial reports, marked-up legal documents, patient records with colour-coded sections. These are exactly the documents you do not want to upload.

FixMyPDF uses the browser’s built-in Canvas API and PDF.js to process everything locally. Your file is read into memory, converted page by page, and returned as a download. Nothing leaves your device.

Frequently asked questions